ed 5.9GHz for V2V and V2I communication for vehicle safety applications that is highly compatible with the U.S. DSRC WAVE band, allowing the usage of similar antennas and wireless transceivers in the platform.

The IEEE 802.11p standard was designed on top of the ASTM E2213-033 standard, which is a predecessor on ve-hicle-based communication networks. It includes the architecture for VAN to enable vehicle safety and non-safety transactions such as toll collection and traffic mapping. The goal in IEEE 802.11p is providing a framework to incorporate VANs throughout a nation’s road infrastructure with sufficient V2V and V2I communication features de-ployable as needed.

A higher-layer standard, which IEEE 802.11p is based upon, is the IEEE 1609 standard46 providing ubiquitous vehicular communication among different automobile vendors and manufacturers. IEEE 1609 includes a family of standards for WAVE. It defines the architecture, organization, management structure, communication model, security mechanisms and physical access. These features, collectively, facilitate secure V2V and V2I wireless communication in a variety of applications including traffic management, active safety services, or automated tolling. IEEE 1609 includes a subset of standards, each particularly designed to address a specific purpose in WAVE:

IEEE P1609.1 is the resource manager that identifies the key components of the WAVE system architecture. It defines the communication formats such as command message and data storage formats and resources used among all nodes of the architecture. This standard also indicates that OBEs and mobile platforms are supported in WAVE.

IEEE P1609.2 addresses the security issues in WAVE by defining secure message formats. Basically, this standard takes care of secure message management by specifying how secure messages are processed once they are exchanged.

IEEE P1609.3 is the network pro-
tocol layer standard in WAVE that
also supports secure message data
exchange. In addition to defining net-
work and transport layer services such
as routing, this standard also provides
a substitute for IPv6 by defining WAVE
short messages. This is WAVE-specific,
and can be used by most applications.
Moreover, the Management Informa-
tion Base (MIB) for the WAVE protocol
stack is also defined in this standard.

Top challenges

User-Defined Protocols. While the IEEE VAN standard has been recently released, user-defined protocols are needed to allow researchers and industry work on various applications, prototypes, and products.

Modified 802.11. Vehicular networks demand robust wireless connectivity for high-speed mobile outdoor environments. The original IEEE 802.11 standard does not meet these requirements, and thus, there is a pressing need for a modified version of this standard for VAN applications. The problems of 802.11 mainly include mobility, multi-path propagation due to reflection in non-line-of-sight conditions, RF Doppler effect, and low network bandwidth of 2Mbps. 17 Security challenges such as incorporating authentication features and encryp-tion/decryption methods are also of concern. The IEEE 802.11p technology should be deployed in VAN as complementary technology to WiFi, 3G, and WiMAX to address the issues noted here, and enable V2I and V2V for safety and emergency communications.

Scalability of 802.11p. The current
MAC parameters of the IEEE 802.11p
protocol are not efficiently configured
for a potential large number of vehi-
cles. The efficiency, performance, and
throughput decrease as the number of
vehicles increases. 47 Therefore, central-
ized or distributed techniques that com-
pute/estimate the number of communi-
cating vehicles in a geographical area
should be taken into consideration.
Furthermore, in the current 802.11p
protocol, the number of collisions dra-
matically increases as the number of
vehicles increases. 10 On the other hand,
issues such as packet loss come into the
picture as the speed of vehicles increas-
es. 35 For all these reasons, advanced
techniques should be integrated within
the IEEE 802.11p standard to overcome
such scalability issues.

existing Wireless solutions

Cohda Wireless Ltd, a developer in the area of safe vehicle and connected vehicle designs ( www.cohdawireless. com), has addressed the mobility and outdoor Non-Line-Of-Sight (NLOS) issues due to long delay spread and multipath propagation by designing a radio on Wi-Fi chipsets. Particularly, Cohda wireless has implemented the MK2 WAVE-DSRC Radio, which is an IEEE 802.11p-compliant device suitable for V2V and V2I communication in WAVE. At present, Atheros ( www.atheros. com) and Broadcom ( www.broadcom. com) have, at least partial support for 802.11p. There are other device manufacturers that have developed 802.11p- compliant systems (for example, www. aradasystems.com and www.redpines-ignals.com). All these solutions suggest that 802.11p is the front-runner for serious deployment in VAN.

Simultaneously in academia, researchers have devised smart adaptive antennas and cooperative/cognitive radios for wireless connectivity in vehicular networks. 53

 

security and Privacy of Van A number of security mechanisms has been integrated within the IEEE P1609.2 standard, 46 enabling security and privacy features for vehicle-area-networks. These issues are of significant importance and should be devised before VAN becomes fully operational. Imagine how false or stolen data such as driver behavior, vehicle functional information, environmental hazards, or road condition data could cause